Leishmaniasis (cont.)

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

How is leishmaniasis diagnosed?

In countries where the disease is common, patients with compatible clinical symptoms and findings can be presumed to have leishmaniasis. Other patients require definitive diagnosis, which is done by examining tissue under a microscope (Figure 5) to detect the parasite or through a blood test to detect antibodies (see below). There is a skin test called the Montenegro skin test, but it is imperfect and not used for diagnosis of disease.

It is important to remember that there are many diseases that can cause fever, weight loss, skin lesions, or enlargement of organs. Conditions like malaria, typhoid fever, toxoplasmosis, Chagas disease, schistosomiasis, tuberculosis, histoplasmosis, syphilis, and others may mimic some symptoms of leishmaniasis so a definitive diagnosis is useful to rule out these other diseases.

In VL, tissue for microscopic examination may be obtained from the spleen, liver, or bone marrow. Some patients with VL, especially those from Sudan, have enlarged lymph nodes that can be biopsied. In cutaneous leishmaniasis or mucocutaneous disease, biopsies or scrapings are taken from the affected area. Special stains are used on biopsies, some of which employ polymerase chain reaction (PCR) methods. The tissue can also be cultured on special media, which allows the parasite to multiply and be detected more easily under the microscope. In the United States, the Centers for Disease Control and Prevention (CDC) should be contacted to obtain advice and the appropriate media.

Antibodies in the blood can be detected using enzyme-linked immunosorbent assays (ELISA). Antibody assays are usually positive in VL but are variably positive in CL and ML because these conditions do not stimulate reliably and consistently elevated antibody titers in the blood.